package com.zhen.netty.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Date;
import java.util.Iterator;
import java.util.Set;

/**
 * Created with IntelliJ IDEA.
 * User: zhen-desktop
 * Date: 2018/11/29
 * Time: 22:58
 */
public class MultiplexerTimeServer implements Runnable{

    private Selector selector;

    private ServerSocketChannel serveChannel;

    private volatile boolean stop;

    public MultiplexerTimeServer(int port) {

        try{
            selector = Selector.open();
            serveChannel = ServerSocketChannel.open();
            serveChannel.configureBlocking(false);
            serveChannel.socket().bind(new InetSocketAddress(port),1024);
            serveChannel.register(selector, SelectionKey.OP_ACCEPT);
            System.out.println("The time server is start in port : " + port);
        }catch (IOException e){
            e.printStackTrace();
            System.exit(1);
        }
    }

    public void stop(){
        this.stop = true;
    }



    /**
     * When an object implementing interface <code>Runnable</code> is used
     * to create a thread, starting the thread causes the object's
     * <code>run</code> method to be called in that separately executing
     * thread.
     * <p>
     * The general contract of the method <code>run</code> is that it may
     * take any action whatsoever.
     *
     * @see Thread#run()
     */
    @Override
    public void run() {
        while(!stop){
            try{
                selector.select(1000);
                Set<SelectionKey> selectedKeys = selector.selectedKeys();
                SelectionKey key = null;
                for (Iterator<SelectionKey> it = selectedKeys.iterator();it.hasNext();){
                    key = it.next();
                    it.remove();
                    try{
                        handleInput(key);
                    }catch (Exception e){
                        if(key != null){
                            key.cancel();
                            if(key.channel() != null){
                                key.channel().close();
                            }
                        }
                    }
                }
            }catch (Throwable t){
                t.printStackTrace();
            }
        }

        if (selector != null) {
            try{
                selector.close();
            }catch (IOException e){
                e.printStackTrace();
            }
        }
    }

    private void handleInput(SelectionKey key) throws IOException {
        if(key.isValid()){
            if(key.isAcceptable()){
                ServerSocketChannel ssc = (ServerSocketChannel)key.channel();
                SocketChannel sc = ssc.accept();
                sc.configureBlocking(false);
                sc.register(selector,SelectionKey.OP_READ);
            }

            if(key.isReadable()){
                SocketChannel sc = (SocketChannel)key.channel();
                ByteBuffer readBuffer = ByteBuffer.allocate(1024);
                int readBytes = sc.read(readBuffer);
                if(readBytes > 0){
                    readBuffer.flip();
                    byte[] bytes = new byte[readBuffer.remaining()];
                    readBuffer.get(bytes);
                    String body = new String(bytes,"UTF-8");
                    System.out.println("The time server receive order : " + body);

                    String currentTime = "QUERY TIME ORDER".equalsIgnoreCase(body) ? new Date(System.currentTimeMillis()).toString() : "BAD ORDER";
                    doWrite(sc,currentTime);
                }else if(readBytes < 0){
                    key.cancel();
                    sc.close();
                }else{

                }
            }
        }
    }

    private void doWrite(SocketChannel channel, String response) throws IOException{
        if(response != null && response.trim().length() > 0){
            byte[] bytes = response.getBytes();
            ByteBuffer writeBuffer = ByteBuffer.allocate(bytes.length);
            writeBuffer.put(bytes);
            writeBuffer.flip();
            channel.write(writeBuffer);
        }
    }
}
